Gage.



E. R. SEWARD. I

GAGE. APPLIGATION FILED MAR.19, 1907.

919,477. I I Patented Apr. 27, 1909.

OFFICE.

ERNEST R. SEWARD, OF HARTFORD, CONNECTICUT.

GAGE

Specification of Letters Patent.

Patented April 27, 1909.

Application filed. March 19, 1907. Serial No. 363,171.

To all whom it may concern:

Be it known that I, ERNEST R. SEWARD, a citizen of the United States,and a resident of Hartford, in the county of Hartford and State ofConnecticut, have invented a new and Improved Gage, of which the following is a specification.

My invention relates more especially to the class of machinists toolsemployed for determining the pitch diameter of screw threads, and theobject of my invention is to provide a device of this class by means ofwhich the pitch diameter of screws of widely varying sizes may beinstantly determined, the exact measure being shown by the gage.

A device in the use of which these objects may be attained isillustrated in the accompanying drawings, in which Figure 1 is a view inside elevation of a tool embodying my invention, with parts out insection to show construction. Fig. 2 is a view in elevation of thedevice in a plane at right-angles to the plane of Fig. 1, with partsbroken away to show the construction, arrangement and method ofoperation of the means for holding the anvilcarrier upon the extensionof the frame that supports it, the latter being but slightly exposed inthis view. Fig. 3 is a detail view showing the application of thedevice. Fig. 1 is an elevation of a large screw illustrating theprinciple involved in the use of my invention.

In the accompanying drawings the numeral 1 denotes a frame or body parthaving at one end a thimble 2 for operating the micrometer screw 3. Thisthimble and its connection with the screw 3 are of ordinary andwell-known construction, and further and detailed description istherefore deemed unnecessary herein, it being suflicient to state thatthe connection is such that the degree of rotary movement of the thimble2 imparts to the screw a much less degree of longitudinal movement.

The frame 1 is generally of the usual C shape common to devices of thisclass. That end of the frame opposite the thimble 2 is formed intoanextension or neck 4, preferably of tubular form and having a centralopening 5. This extension is located with its axis at an angle to theaxis of the screw 3. The openingin the extension 4 is enlarged as at ,6and has its inner surface screw threaded for the reception of an anvilfeed screw 7. This feed screw has a shank 8 extending into the opening 5and is threaded to lit the thread in the opening or chamber 6. A flange9 is formed on this feed screw and a head 10 is secured thereto as bymeans of inter-engaging screw threaded parts. This provides an annulargroove extending about the feed screw within which a lip 11 from ananvil sleeve 12 extends. The head 10 is graduated, as shown in Fig. 2 ofthe drawings, these graduations operating in connection with an indexpoint 13 on the sleeve 12. This sleeve bears an anvil rest 14. in whichan anvil 15 is located. A clamp screw 16 supported in the sleeve 12 andextending transversely across the parts may be employed for holding thesleeve 12 in any position of adjustment.

By my improved gage I have provided means whereby the anvil may be setin a position determined by the pitch of the screw, and themicrometerscrew then being set in position to allow the screw to bemeasured to pass through between the ends of the anvil and themicrometer screw, the reading of the latter will give the exact pitchdiameter of the screw, and the gage may be employed to measure the pitchdiameters of screws varying greatly in size.

In the form shown herein for holding the sleeve the screw 16 is looselyfitted within a sleeve 17, the end of which abuts against the neck 4, asshown in Fig. 2 of the drawings. The tips of the micrometer screw and ofthe anvil have their opposite sides arranged at practically the sameangle each to the other as the angle of the two sides of the groove in athread to be measured, so that said screw and tip take their bearing forpractically the full depth of the thread. In fact, the ends of the tipsare relieved slightly so that they shall not seat at the bottom of thegroove, owing to the fact that the bottom of the groove for its fullextent, or the bottom of the grooves on different screws, are not liableto be uniform. v

In order to better illustrate the principle involved in using myinvention I refer to Fig. 1 which shows a screw a the pitch diameter ofwhich, indicated by m, it is desired, it will be assumed, to ascertain.This dimension, as is well known, equals the external diameter, 3 lesstwice one-half the i of the thread, a. The anvil or part 15 havdepth,.2, of the thread, or, expressed as an equation,

which reduced is X=yz. It is well nigh the universal practice in makingscrews with V-threads to have the adjacent faces form an angle of 60,this being followed whether the thread be fine or coarse, and whetherout upon a large or small cylinder; and from this it follows that thedepth of the thread of such a screw is always proportionate to itslinear pitch, without reference to the size of the cylinder upon whichthe thread is cut, so

- that in a screw of a certain pitch the depth,

e, of its thread is always the same.

In using the gage herein described the parts are set as represented inFig. 1, that is, with the points or ends of the parts 3 and 15 in linewith each other and in engagement-actual or theoretical. If it werepractically possible to make the points of the parts 3 and 15theoretically correct at their extreme ends, and if it were also thecommon practice to make the bottoms of the threads likewisetheoretically perfect, then it would not matter what were the shape ofthe parts 3 and 15 so long as their points or ends might engage with thebottoms of the threads. But since this theoretical accuracy isimpractical I have found it desirable to so shape the ends of the parts3 and 15 that they will properly seat themselves in the grooves betweenadjacent threads, when the gage is correctly applied to a screw. Thebest form to give the ends of the contact parts of the gage to securethis result, though not the only form by any means, is that illustratedin the drawings. Here they are shown as of conical shape with sidessloping 30, and these cones may be slightly truncated, as alreadystated, so that any imperfection in the finishing of the bottoms of thethreads will not interfere with the accurate working of the instrument.Another advantage incident to the conical shape of the points of theparts 3 and 15 is that the latter may be adjusted relative to the formerwithout interfering therewith, the point of the part 15 moving past theother part with their side faces in engagement.

To ascertain the pitch diameter of the screw a, the number of threads tothe inch is first ascertained; and then, by reference to a tableprepared for that purpose, the anvil is adjusted to the proper positionfor measuring a screw of that pitch. lVhen this adjustment has been madeit will be found that the point, theoretical or actual, of the part 15,will have been carried laterally a distance equal to the distance, 20,between threads, and at the same time will have been carried inward adistance equal to the depth ing been set, the micrometer stem 3 isadjusted to fit the screw, as indicated in dotted lines in Fig. 4, whenthe reading of its scale will be the true pitch diameter of the screw a.The diametric distance separating the points of the parts 3 and 15,indicated in Fig. 4 by y, is not the pitch diameter, nor is it thedistance indicated by the micrometer gage, when the parts are adjustedas represented in the drawings. What the micrometer gage does indicateis the distance, y, plus the depth of the screw thread, a, the anvilpoint having been moved inward beyondthe point of the part 3 the latterdistance before any adjustment of this part 3 was begun. By reference toFig. 4 it will be seen that y+2:g z, or m in either case, 00 indicatingthe pitch diameter.

What I claim as my invention and desire to secure by Letters Patentis 1. A frame, a micrometer screw having a pointed end mounted in oneend of the frame, an anvil having a contact end that is adapted to bebrought opposite to and in axial alinement with the micrometer screw, acarrier for the anvil, and a guide on the frame for directing themovements of said carrier arranged to maintain the axis of the anvilparallel with that of the micrometer, and to cause the anvil to movebodily with its contact end traveling along a line in clined to the axisof the micrometer screw.

2. A C-shaped frame, a micrometer screw having a pointed end adapted toengage a threaded member and mounted in one end of the frame, anextension at the opposite end of the frame fixed in a position inclinedto the axis of the micrometer screw, an anvil-carrier mounted upon andmovable along the said extension, and an anvil adapted to engage withthe screw thread supported by the said carrier.

3. A base, a micrometer screw mounted in the base, an anvil mounted inthe base and having a pointed end, a screw threaded into the base andlocated at an angle inclined to the axis of the micrometer screw, andconnections between said anvil and screw for moving the former.

t. A base, a micrometer screw mounted in the base, an anvil sleevemounted in the base and movable in a plane inclined at an angle to theaxis of the micrometer screw and to the axis of the screw the thread ofwhich is to be measured, and a screw threaded into the base and inengagement with said sleeve.

5. In a micrometer gage for measuring screws, a frame, a micrometerscrew mounted therein, an anvil movable bodily in the frame and having acontact end to engage a screw threaded member, and means for 10- catingthe contact end of the anvil in different positions along a lineparallel with a side of a thread of the screw to be measured when thegage and screw are in proper relation for taking a measurement.

6. In a micrometer gage for measuring screws, a frame, a micrometerscrew mounted in the frame, an anvil mounted in the frame and arrangedto move in planes parallel with a face of the thread of the screw to bemeasured when the screw is properly applied to the gage, and means formoving and setting the anvil.

7. In a micrometer gage for measuring screws, a frame, a micrometerscrew having l l l l l a contact end shaped to be seated in a groovebetween screw threads, a movable anvil opposite the micrometer screwalso shaped to be seated in the groove between the threads, and meansfor accurately setting the anvil, in different positions along a lineparallel with a side face of the thread to which the gage may beproperly applied.

I, ERNEST R. SEVARD. Witnesses EDWIN O. DICKENSON, ARTHUR B. JENKINS.

